Incinerator

ABSTRACT

The present invention relates to a commercial or industrial type incinerator and more particularly to an incinerator which is capable of disposing of combustible waste containing a substantial percentage of plastic materials without creating attendant atmospheric pollutants.

United States Patent 1191 Atkin Aug. 13, 1974 [5 INCINERATOR 3,605,654 9/1971 Bowles, Jr 110/8 3,645,218 2 1972 Davis llO/8 [75] Inventor: Robert San Jose 3,680,500 8/1972 Pryor 110/8 [73] Assignee: Pyrocom, Inc., Campbell, Calif, 3,736,888 6/1973 Lomax 110/8 [22] Flled: May 1973 Primary Examiner-Kenneth W. Sprague [2]] Appl. No.: 364,898 Attorney, Agent, or Firm-Robert B. Crouch [52] US. Cl. 110/8 A, 1lO/8 C, 1lO/18 C [57] ABSTRAT [51] Int. Cl. F23g 5/12 1 [58] Field of Search 110/8 R, 8 c, s A, 15, The P P i relates 3 110/18 R 18 C dustrlal type mcmerator and more part1cularly to an incinerator which is capable of disposing of combusti- [56] References Cited ble waste containing a substantial percentage of plastic materials without creating attendant atmospheric UNITED STATES PATENTS pollutants 3,323,475 6/l967 Melgaard [IO/l8 3,490,395 1/1970 Boyd et al 1 10/18 5 Claims, 4 Drawing Figures PAIENIE we 1 3mm llllklmm 2 RN INCINERATOR BACKGROUND Combustible wastes from commerical and industrial establishments have generally been disposed of by incineration, either on site or at a central location. However, the rising incidence of usage of plastic and synthetic materials in packaging, utensils, furnishings, clothing and equipment of various kinds has created a major problem in waste disposal. When waste containing a significant percentage of plastic or synthetic materials, e.g., in excess of percent, are incinerated by conventional methods, pollutants, in the form of carbonyls, hydrocarbons, particulants, etc., are created. The discharge of such pollutants into the atmosphere is now regulated by federal and state agencies which have the power to assess fines and/or enjoin violations. As a consequence, many establishments have restored to alternative methods of disposal of their waste materials, such as compaction and burial. This approach solves the immediate disposal problem, but is expensive in comparison with incineration and poses a long-term uncertainty, since the plastic materials are not biodegradable and thus remain in their existing form for an indefinite period. In addition the amount of land which is suitable for land fill within reasonable proximity of urban centers is rapidly being depleted and certain wastes, particularly hospital-type wastes, give rise to the possibility of contamination of the water table when buried in a land fill.

INVENTION The incinerator of the present invention avoids the shortcomings of the prior known methods of disposal of combustible waste materials by provision of means for incinerating combustible wastes which include up to 100 percent plastic or synthetic materials. This is accomplished by provision of a controlled, stabilized process of combustion within the incinerator, wherein the solid wastes are volatilized at a controlled rate in the presence of a flame, the resultant combustion gases are combined with excess oxygen and are burned in an oxidizing flame, the remaining combustion products are then thoroughly mixed with the remaining excess oxygen at an elevated temperature and then accelerated into another oxidizing flame where the residue of the plastic materials is completely consumed.

Other objects and many of the attendant advantages of this invention will be readily appreciated and the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing wherein;

FIG. I is a plan view of an incinerator according to the present invention,

FIG. 2 is an elevation view of the incinerator of FIG.

FIG. 3 is a sectional view taken along lines AA of FIG. 1;

FIG. 4 is a sectional view of the third stage chamber taken along line BB of FIG. 2.

Referring to FIGS. I and 2 of the drawings, the incinerator of the present invention includes a primary combustion chamber 11, a secondary combustion chamber 12 and a third stage combustion chamber 13. Each of the chambers is formed of sheet steel with a lining of a suitable refractory material. The incinerator includes an elongated structurehaving sidewalls l4 and 15 supported on a concrete base 16 and joined by an arcuate top 17. End walls 18 and 19 close the front and rear respectively of the structure. A large opening in the front wall 18 is covered by a door 21 which is hingedly mounted to the wall as at 22. An air inlet 23 is provided in the door by means of a circular plate 24 which is provided with a cutout. The plate 24 is rotatably mounted on the door with the cutout therein in overlapping relationship with similar opening through the door, such that the effective size of the air inlet through the door can be varied by rotation of the plate. A burner 25 with a blower attached is mounted in the side wall 15 near the front wall. An interior partition 26 of fire brick or refractory material shown in dotted line, divides the interior of the structure and provides communication through a port (not shown) from the primary chamber 11 to the secondary chamber 12. A number of louvers 27 are set in the arcuate top and pro vide an air inlet adjacent the rear wall 19. A duct 28 extends between the rear of the secondary chamber and the third stage chamber 13. A second duct 29 connects the interior of the third stage chamber to the low pressure side of a blower 31. The high pressure side of the blower is connected through a duct 32 to an exhaust stack 33.

Referring to FIG. 3, the interior of the secondary chamber adjacent the louvered section 27 is walled off by means of a horizontal platform 34 and a stub wall 35 of tire brick or refractory material. A burner 36 with a blower attached is mounted in the stub wall 35 above an opening 37 which is titted with an adjustable damper 38. The third stage chamber is provided with a vertically extending, generally cylindrical, exterior wall 39 mounted on a concrete base 41. A generally cylindrical, interior wall 42 is concentric with, and spaced from the wall 39 to define an annular space 43 therebetween. A series of spaced ports 44 extend through the interior wall 42 adjacent the base 41. A horizontal shelf 45 connects the approximate vertical midpoint of the external wall and internal wall and extends over approximately 270 of the annular space. A series of baffles in the form of a grid 46 covers the duct 28 at its junction with the external wall. An annular top 47 is mounted on the third stage chamber and seals off the annular top 47 is mounted on the third stage chamber and seals off the annular space 43. A generally cylindrical section 48 protrudes from the upper surface of the top and communicates with the interior 49 of the third stage chamber. As illustrated in FIG. 1 duct 29 is connected to the section 48. A passageway 51 which is walled off from the annular space 43 extends between the external wall 39 and the internal wall 42. A burner 52 is mounted in the passageway and communicates with the interior space 49.

OPERATION Particulants, such as carbon, carbonyls or globs of material, drcrease in size as they burn. This reduction of diameter and surface area occurs as the material is transformed into a gaseous state and it occurs at a rate which is dependent on the various parameters of the combustion environment. As the particle enters the combustion environment, its temperature rises, it begins to give off gases and its surface area decreases. The most efficient combustion process is one that will heat the particle in the shortest distance, reduce the surface area to zero in the shortest length of time and then most rapidly diffuse and burn the gases generated as the particle disintegrated.

One of the chief problems in existing combustion processes is that the gases being generated by deterioration of the particle act as an envelope around the particle and inhibit the heating, and especially the surface reduction and gas diffusion, processes. The incinerator and combustion process of the present invention effectively overcome this problem by acceleration of the particles to a high velocity just as they enter the flame front, so that the gases generated stream behind the particle like a comet. Thus, the particle is left free of any insulating gaseous field, so that the surface reduction continues at the maximum rate. Additionally, the particle enters the flame front at an obtuse angle, so that the streaming gases behind the particle rapidly diffuse into the excess oxygen present and are immediately consumed.

In the operation of the present incinerator, the products of combustion are drawn through the various stages of the incinerator by the blower 31 which discharges them into the stack 33. Thus, the incinerator operates at less than atmospheric pressure and the oxygen to sustain combustion is drawn into the chamber through air inlet 23, opening 37 and the blowers associated with burners and 36. The primary chamber is charged with combustible waste material through door 21. The waste material is supported on a gate structure (not shown) and ignited by heat and flame from the burner 25. The plate 24 is rotated to adjust the size of the air inlet 23 and limit the quantity of air drawn into the primary chamber, thereby controlling the rate of combustion within the primary chamber. It should be noted that it is not the intent to completely consume the wastes within the primary chamber, but instead primarily to convert them from a solid to a gaseous state. By limiting the amount of air drawn into the primary chamber the rate of combustion of the wastes is controlled and the temperature within the primary chamber can be effectively limited. The temperature within the primary chamber is held to a maximum of approximately l,000F. lnasmuch as air is supplied through inlet 23 and from the blower associated with burner 25, the flame within the primary chamber may be a reducing flame, an oxidizing flame or a combination of both depending upon the type of waste material being consumed and the rate of combustion desired. The combustion gases from the first stage pass through a port or opening (not shown) in partition 26 into the secondary combustion chamber. Air is drawn into the secondary chamber through louvered section 27 and opening 37 and from the blower associated with burner 36. The damper 38 is adjusted to permit sufficient air to be drawn through opening 37 to provide within the secondary chamber an excess of oxygen beyond that required for complete combustion of the gases from the primary chamber. The combustion products, or smoke, from the primary chamber, are mixed with the air from opening 37 and the blower and are fired by the secondary burner 36. This mixing and burning consumes the previously unburned particles derived from natural, i.e., non-plastic, products. The secondary stage burning does not completely consume the particles derived from plastic and synthetic material but rather heats them and the excess oxygen to an elevated temperature and initiates burning of them. The combustion products from the secondary stage and the excess air are di- LII rected into duct 28 through grid 46 and into the annular space 43 of the third stage chamber. The grid of baffles 46 creates turbulence in the flow from duct 28 and enhances the mixing of the excess air with the combustion products from the second stage. The second stage combustion products and excess air flow from left to right around the annular space above the shelf 45 while mixing continues. The mixture is held at an elevated temperature by head radiated from chamber 49 and by the fact that some burning continues within the space 43. Since the shelf 45 extends over only approximately 270 of the annular space, continued rotation of the gases within the space causes the mixture to descend through the opening in the shelf and continue rotation along a spiral path below the shelf. By the time the combustion gases and excess air reach the base 41 of the chamber, they are thoroughly mixed and have been maintained at an elevated temperature during the entire path through the annular space. The air-smoke mixture is then drawn through the ports 44 which are arranged in a circle around the flame front from burner 52. The mixture is accelerated to a high velocity through the ports and is immediately and thoroughly interspersed with the flame from the burner. When the air-smoke mixture is immersed in the flame front from burner 52 the plastic particles are completely consumed.

Sufficient air is passed through opening 37 to insure that there is approximately 18 percent excess oxygen in the air-smoke mixture entering the third stage. Just enough air is injected at the third stage to sustain the burner flame without cooling the air-smoke mixture. The third stage combustion chamber 49 is maintained at a temperature of from l,600F to 1,800F in order to completely burn the plastics without creation of nitrogen-oxygen combinations which in themselves are pollutants. In this regard the provision of a third stage combustion chamber, rather than an afterburner in the stack, is important to allow maintenance of thre required temperatures and to permit sufficient residence time of the particles in the combustion atmosphere to allow complete consumption of the particles and the gases emitted.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. An improved incinerator for consuming combustible wastes which include a significant percentage of plastic or other synthetic materials including:

first stage combustion means for converting the wastes to a gaseous form;

means for controlling the rate of combustion in the first stage to limit the temperature therein below 1,000F; second stage combustion means for consuming the gases from the non-plastic wastes and initiating combustion of the gases from the plastic wastes;

means for injecting excess oxygen into the second stage means;

means for creating turbulence within the flow of gases from the second stage means to ensure thorough mixing of the gases and excess oxygen;

third stage combustion means including an oxidizing flame front;

and means for accelerating the gaseous mixture from 4. An improved incinerator as set forth in claim 1 the second stage into the flame front at an obtuse wherein: angle. the third stage combustion means includes two gen- A mp incinerator as Set forth in claim 1 erally cylindrical members positioned in concentric w ereln; 5

relation to define an annular passageway between the two and a cylindrical chamber within the inner member;

means for discharging the secondary products of combustion through the means for creating turbulence into the annular passageway; and

the means for accelerating the gaseous mixture from the second stage includes a series of ports extendthe third stage combustion means is an elongated cylindrical chamber with an oxidizing flame front extending generally radially thereof; and

means for accelerating the gaseous mixture from the second stage and discharging it tangentially of the 10 chamber to create a spiral movement of the gases through the flame front and within the chamber.

3. An improved incinerator as set forth in claim 2 wherein ing through the inner member and connecting the the cylindrical chamber is positioned with its longituannular passageway the cylmdncal m dinal axis extending Vertically; 5. An improved incinerator as set forth in claim 4 the flame front is located adjacent one end of the wherem:

chamber; the cylindrical members are vertically positioned on the means for accelerating and discharging the gases 3 base with a top mgmber Sealing f PP end of i l d dj h fl f m; d the annular passageway and the cylindrical chammeans is provided at the opposite end of the cylindrical chamber for withdrawing the products of comthe flame front is located near the base; and the ports bustion from the chamber and discharging them surround the flame front. into an exhaust stack. 

1. An improved incinerator for consuming combustible wastes which include a significant percentage of plastic or other synthetic materials including: first stage combustion means for converting the wastes to a gaseous form; means for controlling the rate of combustion in the first stage to limit the temperature therein below 1,000*F; second stage combustion means for consuming the gases from the non-plastic wastes and initiating combustion of the gases from the plastic wastes; means for injecting excess oxygen into the second stage means; means for creating turbulence within the flow of gases from the second stage means to ensure thorough mixing of the gases and excess oxygen; third stage combustion means including an oxidizing flame front; and means for accelerating the gaseous mixture from the second stage into the flame front at an obtuse angle.
 2. An improved incinerator as set forth in claim 1 wherein; the third stage combustion means is an elongated cylindrical chamber with an oxidizing flame front extending generally radially thereof; and means for accelerating the gaseous mixture from the second stage and discharging it tangentially of the chamber to create a spiral movement of the gases through the flame front and within the chamber.
 3. An improved incinerator as set forth in claim 2 wherein: the cylindrical chamber is positioned with its longitudinal axis extending vertically; the flame front is located adjacent one end of the chamber; the means for accelerating and discharging the gases is located adjacent the flame front; and means is provided at the opposite end of the cylindrical chamber for withdrawing the products of combustion from the chamber and discharging them into an exhaust stack.
 4. An improved incinerator as set forth in claim 1 wherein: the third stage combustion means includes two generally cylindrical members positioned in concentric relation to define an annular passageway between the two and a cylindrical chamber within the inner member; means for discharging the secondary products of combustion through the means for creating turbulence into the annular passageway; and the means for accelerating the gaseous mixture from the second stage includes a series of ports extending through the inner member and connecting the annular passageway with the cylindrical cHamber.
 5. An improved incinerator as set forth in claim 4 wherein: the cylindrical members are vertically positioned on a base with a top member sealing the upper end of the annular passageway and the cylindrical chamber; the flame front is located near the base; and the ports surround the flame front. 